Something more... a Woody?

[KazooMan]

Yeh, I will have to try a few open chord tunings.  I think that the "real" slide guitar guys always used a cut off whiskey bottle neck as a slide.  Time to head to the store for a good bottle of Kentucky bourbon.

For now my Woody simulator sounds like one of those resonator guitars with a handful of marbles thrown in through the f holes.  Just gotta figure out how to tame the high end a bit. 

[Elijah-Baley]

I got the PCB. My first. Looks very nice!



I have some parts, but I have to wait my next order for all components.

[Elijah-Baley]

Hey guys, I just populated the PCB, with pots and wires, too. Tested it, and it works fine!
Nice sound, not really and realistic acoustic sound, but I knew it and that's ok.
About the trimpot the TH Custom says: «The trimpot is there to adjust the highpass filter. You will need a certain level of signal to generate the right harmonic content. Depending on your pickup this varies. Just dial in the nicest sounding tone.»
Someone knows how I should adjust it? By my ear? I would that it sounds ok with all kinds of guitars, with single coils or humbuckers.

Thank you.

[Mark Hammer]

If I haven't noted it already, faking an acoustic convincingly will usually need an extended frequency response from the amplifier speakers.  Many speakers tend to roll off sharply above 5-6khz, which can take the edge off distortion and overdrive nicely, but takes a lot of the "air" out of even real acoustics.  Indeed, many people who try out "exciter"-type pedals will end up asking "Is this thing even on?" when they try it with an HB-equipped guitar into a regular guitar amp.  Both the pickups and speakers have to be able to provide audible top end for exciters and acoustic simulators to yield anything obvious.

[croatonpj]

I've built one on Mark's schematic (thank you for making this) and it sounds surprisingly well.
I've a strange question: because of personal needs I would like to know if there is a way to turn this circuit into a simple presence boost through a switch that bypasses the tone circuit. If yes I need a help to understand how to place this switch. Thank you anyway.   

[Elijah-Baley]

My pedal Woody is complete!

I tried better, now. It isn't a real acoustic guitar simulator how I expected, and as I can hear in the demo of Boss AC-2 or AC3, or as the Behringer (Boss clone), or as some pedal else.
It is a sort of EQ, mid scooped seems to me. It cannot cut treble and can cut just a bit of the bass. It enhances much treble, instead the bass control is more versatile. The internal trimpot is set to half.

It gets the clean sound, more... clean? bright? maybe get a nicer clean.
I never tried an acoustic simulator, but I think the Woody isn't a real alternative to an acoustic simulator (too bad), but an alternative to the clean sound of the amp in certain case.

Picture later.

[Mark Hammer]

In my defense, when I whipped it up in 2003, the state of acoustic simulation was not what it is now.  I would imagine that any design from that period has been eclipsed many times over.

[Elijah-Baley]

Thanks for reply, Mark. It's ok!

2003? Wow!
I have to say I knew how the woody could to be, before to build it, but I expected too much anyway. My fault.
Nevertheless, it is an interesting pedal.

[thehallofshields]

Is it possible that what the Woody needs is an Expander to get closer to that dreadnought feel?

[Mark Hammer]

As much as I would defend the circuit, adding expansion strikes me as putting lipstick on a pig.

[thehallofshields]

Hah. What about compression before the clipping?

I got this wild idea to swap the LPF and HPF opamps with a Compander chip for respectively boomier lows and more consistent harmonics on the highs.

[rankot]

I've built Woody and it sounds nice, I really like it. But I have a problem - it is rather noisy - noise gets louder when playing and once I stop, it fades. It is high frequency noise and is lowered when I turn down treble pot. Could it be connected to trim pot setting, or there is something else going on? Any hints?

[Elijah-Baley]

Did you build the original schematic version? Which layout?
I excluded the Sabrotone version, a bit different, because somebody got some bad noise.

[rankot]

I used this schematic:



Found here: https://www.diystompboxes.com/smfforum/index.php?topic=77747.msg648685#msg648685

After I noticed noise issue, I found another schematic, marked v1.1 http://diy.thcustom.com/download/acoustic-simulator-v1-1-build-instructions/. It is almost the same as the one I used, except it uses smaller biasing resistors (2M2 instead of 5M1) and has two additional high cut capacitors (C17 and C18).

I have used four NE5532AP, and added 100n multilayer caps to filter power supply noise for every one of them. This is my layout:


So I have added those capacitors (330p and 470p) but it didn't change the noise problem.

[bluebunny]

I built the TH Custom version using the TL074s specified for that build.  No noise that I've detected (in fact, it sounds very good indeed.)  Is it worth trying to swap out your opamps for 072s?

[rankot]

I built the TH Custom version using the TL074s specified for that build.  No noise that I've detected (in fact, it sounds very good indeed.)  Is it worth trying to swap out your opamps for 072s?

Damn, I knew I should put sockets I'll try that as the last option.

[duck_arse]

compare the input oppie in this dia:


with the input in the above "Hammer's Woody". something screwy about the second schem inverting input ......

[rankot]

compare the input oppie in this dia:

with the input in the above "Hammer's Woody". something screwy about the second schem inverting input ......

Have you build it using this schematic?

[Mark Hammer]

Biyang produced a pedal called the "Woody", using the same font for legending as I used in the schematic posted just above.  I originally used the circuit in which the input stage was inverting, and then re-inverted with the output stage to be in phase with the input signal.  Oliver Alex approached me about adapting the basic circuit for use with a single-ended supply, and what you see is what came out of that exchange.  It may well be what Biyang released.  Oliver suggested that using a non-inverting buffer at the input would improve input impedance and noise specs.  I couldn't argue with that.

In some respects, the circuit needs a simple noise gate applied to the "exciter" signal, coming off P1b,  That's the primary source of any noise, given that it boosts only high end.

[duck_arse]

compare the input oppie in this dia:

with the input in the above "Hammer's Woody". something screwy about the second schem inverting input ......

Have you build it using this schematic?

built? no. I'm only scoping the schems provided.